(1) Field of the Invention
The present invention relates to a memory access control apparatus. More particularly, it relates to a memory access control apparatus capable of high speed processing and employing an improved virtual memory system, adapted to output data from a memory to a printer such as a laser printer.
(2) Description of the Related Art
A related art is disclosed in Japanese Patent Application No. 58-117405, filed on June 29, 1984, in which a laser printer, for example, is required to continuously print out image data at a high speed, and therefore, a high speed transmission of image data from an image memory to the laser printer is necessary.
Conventionally, in order to continuously read image data, two image memories are provided. Here, while one of the image memories is storing one page of image data, another one page of image data is read from the other image memory. This constitution, however, requires two image memories for simultaneously storing and reading two pages of image data, with the result that memory capacity as a whole must be made large.
It is possible to provide an image memory having a capacity for storing just one page of image data, and new image data may be sequentially written into an area from which the previous image data has been read. This constitution, however, cannot provide a high reading speed when the written image data is not written in sequence from the top to the bottom of the page, as later described in more detail with reference to the drawings.